1. Field of the Invention
The present invention relates to a work fabric feeding device for an automatic sewing apparatus, and more particularly to a work fabric feeding device capable of moving a frame, for holding a work fabric, in an X-direction perpendicular to an arm of a sewing machine and in a Y-direction parallel to the arm of the sewing machine on a working table.
2. Description of the Related Art
Generally, an industrial automatic sewing apparatus includes a sewing machine for forming stitches and a work fabric feeding device for feeding a work fabric to a desired position so that any part of the work fabric may be sewn by the sewing machine. The work fabric feeding device is provided with a frame for holding the work fabric, an X-direction driving mechanism for moving the work fabric holding frame on a working table in an X-direction perpendicular to an arm of the sewing machine, and a Y-direction driving mechanism for moving the work fabric holding frame in a Y-direction perpendicular to the X-direction.
A work fabric feeding device having a feeding device movable in an X-direction and in a Y-direction, and a work fabric holding device fixed on the feeding device is disclosed in Japanese Patent Publication No. 56-8640. The work fabric holding device has a pair of work fabric holding units. Each of the work fabric holding units includes a work fabric holding frame having a lower plate and an upper plate placed on the lower plate, and a lifting device for lifting the upper plate. A work fabric is set on the lower plates when the upper plates of the work fabric holding units are lifted by the lifting devices. After that, the upper plates are lowered by the lifting devices, so that the work fabric is held between the upper plates and the lower plates. Two long slots parallel to an X-direction are formed, one on one end portion of each of the lower plates of the work fabric holding units. The work fabric holding units are fixed to the feeding device by screws inserted into the long slots of the lower plates. The positions where the work fabric holding units are fixed to the feeding device can be adjusted in the X-direction by loosening screws.
Accordingly, the work fabric holding device can hold work fabric having various sizes by adjusting the positions where the work fabric holding units are fixed to the feeding device.
In the above mentioned work fabric feeding device, the position where each work fabric holding unit is fixed to the feeding device can be only adjusted within a predetermined area corresponding to the length of the long slots formed on the lower plate. Therefore, in the situation where the size of a work fabric is changed to extend beyond the predetermined area, the work fabric holding frame having the lower plate and the upper plate has to be changed for another work fabric holding frame which is more suitable for the size of the work fabric. However, it is impossible to exchange only the work fabric holding frame for another work fabric holding frame in the device of Japanese Patent Publication No. 56-8640 because the lifting device is fixed to the work fabric holding frame. Accordingly, a pair of work fabric holding units including the work fabric holding frame and the lifting device have to be entirely exchanged for another pair of work fabric holding units.